You have a SQL pool in Azure Synapse. You discover that some queries fail or take a long time to complete. You need to monitor for transactions that have rolled back. Which dynamic management view should you query?

You can use Dynamic Management Views (DMVs) to monitor your workload including investigating query execution in SQL pool. If your queries are failing or taking a long time to proceed, you can check and monitor if you have any transactions rolling back.
Example: -- Monitor rollback SELECT SUM(CASE WHEN t.database_transaction_next_undo_lsn IS NOT NULL THEN 1 ELSE 0 END), t.pdw_node_id, nod.[type] FROM sys.dm_pdw_nodes_tran_database_transactions t JOIN sys.dm_pdw_nodes nod ON t.pdw_node_id = nod.pdw_node_id GROUP BY t.pdw_node_id, nod.[type]
Reference: https://docs.microsoft.com/en-us/azure/synapse-analytics/sql-data-warehouse/sql-data-warehousemanage-monitor#monitor-transaction-log-rollback